Recently in a contest there was a DP problem which used a prefix-sum concept. I tried to implement it in bottom-up as well as in top-down. The bottom-up one got AC'ed but the top-down got a TLE on Test 3. I understand the reason for TLE but I am not able to implement that bottom-up prefix idea for this. Any ideas on how to solve the problem using top-down approach?
Problem link = http://mirror.codeforces.com/contest/1068/problem/D
Top-Down solution = https://pastebin.com/VYsA7cXj
Bottom-up solution = https://pastebin.com/5RryJeh5
You can add 1 more DP for calculating prefix sum http://mirror.codeforces.com/contest/1067/submission/44793804
Thanks for this idea. It worked. Btw is there a formal method on the usage of simultaneous DP functions to solve a problem.